Add missing error messages for container modules (pytorch#29991)

Summary:
Container `Module`s, including `ModuleList`, `ParameterList` and `ParameterDict`, should not be called like a regular `Module`.
This PR add error messages for these special modules.
Pull Request resolved: pytorch#29991

Differential Revision: D19698535

Pulled By: ezyang

fbshipit-source-id: fe156a0bbb033041086734b38f8c6fde034829bf

torch/nn/modules/container.py

@@ -211,6 +211,9 @@ def extend(self, modules):
             self.add_module(str(offset + i), module)
         return self
 
+    def forward(self):
+        raise NotImplementedError()
+
 
 class ModuleDict(Module):
     r"""Holds submodules in a dictionary.
@@ -451,6 +454,9 @@ def extra_repr(self):
         tmpstr = '\n'.join(child_lines)
         return tmpstr
 
+    def __call__(self, input):
+        raise RuntimeError('ParameterList should not be called.')
+
 
 class ParameterDict(Module):
     r"""Holds parameters in a dictionary.
@@ -590,3 +596,6 @@ def extra_repr(self):
             child_lines.append('  (' + k + '): ' + parastr)
         tmpstr = '\n'.join(child_lines)
         return tmpstr
+
+    def __call__(self, input):
+        raise RuntimeError('ParameterDict should not be called.')